1. Field of the Invention
The present invention is concerned with an apparatus and method for testing strings of miniature incandescent light bulbs to locate inoperative bulbs. Strings of miniature incandescent light bulbs are extremely popular currently for various decorative purposes. One of the most common is for decoration of Christmas trees. The sets are usually strung in series with a minimum of 15 bulbs or more. Since the lamp filaments are generally 2.5 to 7 volts and in series, the total filament voltage should add up to 110 to 120 volts of common household current. Sets with large numbers of bulbs are generally divided into multiple sections in which the bulbs in each section are connected in series. When one bulb fails, a whole section fails to light and it is very frustrating and time consuming to locate and replace the failed bulb. Usually many bulbs have to be checked and replaced before finding the failed bulb.
While there are presently various apparatus available for testing individual bulbs there is no apparatus presently known which is inexpensive, simple to use and can be used to rapidly locate the failed bulb by removing one bulb and connecting the apparatus of the present invention to the bulb socket to determine if that is the failed bulb and if it is not, the direction on the string of bulbs to the location of the failed bulb.
2. Prior Art
U.S. Pat. No. 4,943,752, Todd. While this reference specifically discloses a Christmas tree lamp tester which is simple and utilizes a portable 9 volt battery, it fails to eliminate the need of testing multiple individual lamp bulbs, more or less blindly, since it gives no indication as to the direction of the failed lamp if the socket selected randomly is not the socket of the failed lamp. It uses a piezoelectric circuit suitable for testing Christmas tree lights and related devices. The device, however is suitable for testing only bulbs singularly by inducing a spark across a broken filament of the bulb.
U.S. Pat. No. 5,008,626, Boyd. Also discloses a portable DC miniature lamp tester which includes a translucent plastic body with an open socket for receiving the bayonet end of the lamp, and terminals connecting to a nine volt dry cell battery. This is specifically designed for testing light strings.
The general difficulties in testing Christmas tree lamps are discussed in column 1 of this patent which also refers to the Olin U.S. Pat. No. 3,725,780 which specifically discloses a Christmas tree lamp tester that utilizes a nine volt battery.
U.S. Pat. No. 5,047,721, Farley. Shows a detector for testing a string of lights; i.e. Christmas tree lights by providing means for testing lamps without removing the lamps from the sockets utilizing capacitor plates. Once again, no directional capability is disclosed.
U.S. Pat. No. 3,760,266, Ocasio, Tuman. Shows a simple Christmas tree light socket tester to determine which in a series of lights is burned out. Again, no directional capability is disclosed.